Mobile wireless communication stations (mobile stations), such as mobile phones and tablets have become increasingly popular in recent years. For a user, a mobile station offers a variety of services including those related to software applications such as email, web browsing, and mapping. To provide an enhanced benefit to a user, these services often take into consideration the geographical location of the mobile station (and therefore the location of the user). As an example, a location-based service may provide a user with a map based on the user's location or may provide directions for travel between the user's location and another location. As another example, a location-based service may provide a user with a report of weather or traffic in the user's vicinity. As yet another example, a location-based service may provide a user with a list of services or establishments (e.g., restaurants, parks, or theatres) in the user's vicinity. As such, an important feature of a mobile station is the ability to determine its location.
There are several known mechanisms for determining the location of a mobile station. One or more of these mechanisms may be available depending on a number of factors, including for example, hardware included in or coupled to the mobile station, environmental conditions, and/or the availability of external resources.
A first example of a location determining mechanism uses a satellite-based technology called the Global Positioning System (GPS), and is referred to as autonomous-GPS. In this mechanism, a GPS interface (e.g., having a GPS receiver and a GPS antenna) included in or coupled to the mobile station searches for and acquires satellite signals transmitted from multiple GPS satellites orbiting the earth. Based on an analysis of these signals, the mobile station may then estimate its location.
The autonomous-GPS mechanism is generally known to determine a highly accurate location, however the amount of time required to use the mechanism may be long and considerable system resources may be needed. Indeed, the process of searching for and acquiring GPS signals, analyzing data, and computing the location of the mobile station is time consuming (often taking several minutes) and resource intensive.
A second example of a location determining mechanism is referred to as base station delay. This mechanism is similar to the autonomous-GPS mechanism described above, but uses base station signal delay measurements from a cellular wireless communication system (CWCS) instead of satellite signals. To use the base station delay mechanism, the mobile station typically includes or is coupled to a cellular network interface (e.g., having a cellular antenna), such that the mobile station can operate within a CWCS.
Typically, the base station delay mechanism is less accurate at determining a location than the autonomous-GPS mechanism. However, in many cases, an estimated location is sufficient for providing a location-based service. For instance, an estimated location may be sufficient to perform a database lookup to find pizza restaurants or other attractions or points of interest in the user's vicinity. Likewise, an estimated location may be sufficient to facilitate dispatch of emergency personnel approximately to the location of the user. Also, while the base station delay mechanism may provide relatively less accurate results, the process of determining the location is typically faster than the autonomous-GPS mechanism.
A third example of a location determining mechanism is referred to as assisted-GPS or a-GPS and largely combines the base station delay and the autonomous-GPS mechanisms. In this mechanism, a positioning system uses the estimated location determined using the base station delay mechanism to determine which GPS satellites should be in the sky over the mobile station. Then, the positioning system directs the GPS interface included in or coupled to the mobile station to tune to those particular satellites to receive satellite signals and carry out the remaining process of the autonomous-GPS mechanism. By initially determining the appropriate satellites to obtain signals from, the location is often determined faster that when using the traditional autonomous-GPS mechanism, yet it still provides highly accurate results.
A fourth example of a location determining mechanism is referred to as service set identifier (SSID)-matching. This mechanism is typically available to a mobile station including or coupled to a wireless local area network (WLAN) interface (e.g., including a WLAN antenna) that is configured to connect to a WLAN. An SSID is a unique identifier for a WLAN that is typically publically broadcast by a wireless access point (WAP) connected to the WLAN. By activating a WLAN discovery mode on a mobile station, the mobile station scans for locally broadcasting SSIDs. This is typically performed to facilitate connection between a mobile station and a particular WLAN. However, when using the SSID-matching mechanism, the locally broadcasting SSIDs are instead used to determine a location of the mobile station. To enable use of this mechanism, an SSID-to-location database is maintained that stores records of locally broadcasting SSIDs and their corresponding locations. As such, by querying the database based on a given set of SSIDs scanned by a mobile station, a location of the mobile station can be determined. The SSID-matching mechanism is often reasonably accurate at determining a location and may likely take considerably less time the satellite-based mechanisms described above.